System and method for shifting functionality between multiple web servers

ABSTRACT

A system for providing network functionality from a plurality of network-connected servers to at least one network-connected client computer. A management component is coupled to each of the servers. A shifting component coupled to or within the management component operates to shift data and program components between the networkconnected servers so as to configure a selected server to implement a specified set of functionality. A redirection component responsive to a client request for the specified set of functionality redirects the requesting client to the selected server(s).

BACKGROUND OF THE INVENTION RELATED APPLICATIONS

[0001] The present invention claims priority from U.S. ProvisionalPatent Application No. 60/197,490 entitled CONDUCTOR GATEWAY filed onApr. 17, 2000.

FIELD OF THE INVENTION

[0002] The present invention relates, in general, to network informationaccess and, more particularly, to software, systems and methods forshifting functionality between multiple web servers in a coordinatedmulti-server web site.

RELEVANT BACKGROUND

[0003] Increasingly, business data processing systems, entertainmentsystems, and personal communications systems are implemented bycomputers across networks that are interconnected by internetworks(e.g., the Internet). The Internet is rapidly emerging as the preferredsystem for distributing and exchanging data. Data exchanges supportapplications including electronic commerce, broadcast and multicastmessaging, videoconferencing, gaming, and the like.

[0004] The Internet is a collection of disparate computers and networkscoupled together by a web of interconnections using standardizedcommunications protocols. The Internet is characterized by its vastreach as a result of its wide and increasing availability and easyaccess protocols. Unfortunately, the ubiquitous nature of the Internetresults in variable bandwidth and quality of service between points. Thelatency and reliability of data transport is largely determined by thetotal amount of traffic on the Internet and so varies wildly seasonallyand throughout the day. Other factors that affect quality of serviceinclude equipment outages and line degradation that force packets to bererouted, damaged and/or dropped. Also, routing software and hardwarelimitations within the Internet infrastructure may create bandwidthbottlenecks even when the mechanisms are operating withinspecifications.

[0005] Often, a given entity will provide multiple services usingmultiple servers. For example, a typical suite of Internet servicesmight include a web server, a mail server, a file transfer server, achat server and the like. These servers may execute on a single machineor on multiple machines. Characteristically, the services are providedon a well-defined machine at a known network address so that users canreadily find the machine that is needed to perform a particularfunction. As a result, the functionality is bound to particular servers.More recently, efforts have been made to replicate services ongeographically or topologically distributed servers to improve capacityand performance. However, these solutions maintain the static bindingbetween functionality and particular hardware/software platforms thatimplement the functionality.

[0006] Unfortunately, the ubiquitous nature of the Internet results invariable bandwidth and quality of service between points. The latencyand reliability of data transport is largely determined by the totalamount of traffic on the Internet and so varies wildly seasonally andthroughout the day. Other factors that affect quality of service includeequipment outages and line degradation that force packets to bererouted, damaged and/or dropped. Also, routing software and hardwarelimitations within the Internet infrastructure may create bandwidthbottlenecks even when the mechanisms are operating withinspecifications.

[0007] As a result of this static allocation of functionality, thefunctionality provided by the network-connected servers behavesunpredictably, and may give less than optimal performance. Even wherefunctionality is replicated across multiple servers, service remainssuboptimal. Moreover, load balancing across multiple servers providingreplicated functionality is problematic and often leads to inefficientuse of some resources while other resources are overburdened.

[0008] A particular need exists in environments that involve multipleusers accessing a network resource such as a web server. Web servers aretypically implemented with rich functionality and are often extensiblein that the functionality provided can be increased modularly to providegeneral-purpose and special-purpose functions. Examples includeinformation services, broadcast, multicast and video conferenceservices, as well as most electronic commerce (e-commerce) applications.In these applications it is important to that functionality provided bynetwork-connected resources be provided in a dependable, timely andefficient manner.

[0009] In e-commerce applications, it is important to provide asatisfying buyer experience that leads to a purchase transaction. Toprovide this high level of service, a web site operator must ensure thatdata is exchanged with the customer in the most usable and efficientfashion. An e-commerce transaction may involve several servicesincluding search services, file retrieval services, shopping cartservices and payment services. These varied services are typicallydelivered from a single network node, however the node may be less thanoptimal for a particular customer. Even if multiple server nodes wereavailable, current technology does not provide a way to select aparticular network node. Moreover, there is no mechanism for selectivelyshifting particular functionality among available serving nodes toimprove performance on a function-by-function basis.

[0010] Until now, however, the e-commerce site owner has had little orno control over the transport mechanisms through the Internet thataffect the latency and quality of service. This is akin to a retailerbeing forced to deal with a customer by shouting across the street,never certain how often what was said must be repeated, and knowing thatduring rush hour communication would be nearly impossible. While effortsare continually being made to increase the capacity and quality ofservice afforded by the Internet, it is contemplated that congestionwill always impact the ability to predictably and reliably offer aspecified level of service. Moreover, the change in the demand forbandwidth increases at a greater rate than does the change in bandwidthsupply, ensuring that congestion will continue to be an issue into theforeseeable future. A need exists for a system to exchange data over theInternet that provides a high quality of service even during periods ofcongestion. Many electronic commerce transactions are abandoned by theuser because system performance degradations frustrate the purchaserbefore the transaction is consummated. While a transaction that isabandoned while a customer is merely browsing through a catalog may betolerable, abandonment when the customer is just a few clicks away froma purchase is highly undesirable. However, existing Internet transportmechanisms and systems do not allow the e-commerce site owner anyability to distinguish between the “just browsing” and the “about tobuy” customers. In fact, the vagaries of the Internet may lead to thecasual browser receiving a higher quality of service while theabout-to-buy customer becomes frustrated and abandons the transaction.

[0011] Partial solutions have been implemented by systems that cacheInternet content at multiple distributed locations. In theory, whencontent can be served from a cache location, it can be delivered withlower latency than if it were served from a single originating webserver. However, the content must be copied from its origin to themultiple caches resulting in a tremendous volume of data that must beduplicated and transported. Moreover, it is difficult to keep all of thecache copies coherent with the origin. Furthermore, a cache handles onlystatic content and does not distribute functionality to locations fromwhich it can be more efficiently delivered. Hence, caching is only apartial solution to the many web sites that use dynamically generatedweb pages.

SUMMARY OF THE INVENTION

[0012] Briefly stated, the present invention involves a system forproviding functionality and services from a plurality ofnetwork-connected resources where the mechanisms, such as computer codemodules, implementing the functionality are dynamically assigned to oneor more of the various network connected resources. Users aredynamically and preferably transparently directed to the networkresource in which requested functionality currently resides.

[0013] A system for providing network resources from a plurality ofnetwork-connected resources to at least one network-connected clientcomputer. A management component is coupled to each of the resources. Ashifting component within the management component operates to shiftdata and program components between the network-connected resources soas to configure a selected resource to implement a specified set offunctionality and/or provide a specified set of resources. A redirectioncomponent responsive to a client request for the specified set offunctionality redirects the requesting client to a server offering thespecified functionality.

BRIEF DESCRIPTION OF THE DRAWINGS

[0014]FIG. 1 illustrates a general distributed computing environment inwhich the present invention is implemented;

[0015]FIG. 2a-FIG. 2d show in block-diagram form entity relationships ina system in accordance with the present invention;

[0016]FIG. 3 illustrates in block-diagram form significant components ofa particular implementation of a system in accordance with the presentinvention;

[0017]FIG. 4 shows a domain name system used in an implementation of thepresent invention; FIG. 5 shows front-end components of FIG. 2 ingreater detail;

[0018]FIG. 6 shows back-end components of FIG. 2 in greater detail; and

[0019]FIG. 7 shows a conceptual block diagram of the system of FIG. 2 inan alternative context.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0020] In establishing a network architecture for providing services,there is a continuous compromise made in selecting where, topologically,to locate the hardware and software that provides the services. Inalmost all networks, quality of service amongst the nodes using theservices will differ. This compromise is more apparent in Internet-basedsystems because the differential between users is greater, isunpredictable, and varies significantly over time. Often, the architecthas incomplete knowledge of where the nodes that will access theservices exist. The present invention addresses this compromise byproviding a generic software/hardware infrastructure in which thefunctionality is provided by any or all of a large number of nodes.Functionality is dynamically shifted amongst the available nodes toprovide improved service to all participants.

[0021] The present invention generally involves systems, methods andsoftware for delivering functionality from network-connected resources(e.g., servers) to networkconnected appliances (e.g., clients). It isrecognized that the roles of client and server are flexibly defined inan operating network as some entities play both roles at any given timeand may in fact play both roles at the same time. These terms are usedfor convenience herein for ease of explanation, however, unlessexpressly indicated otherwise the terminology is not to be considered alimitation on the broader teachings of the present invention as setforth in the claims. Further, the examples are directed at web-basedsystems using the Internet, however, more generally, the presentinvention relates to any type of functionality or resources providedover a network and need not be implemented as a web-based system. Hence,unless specified otherwise, a “web server” is synonymous with a “server”or other entity that delivers functionality in response to requests.Likewise, a “browser” is synonymous with a client or other entity thatrequests and uses a particular set of functionality.

[0022] The particular examples herein often refer to a system in which aparticular set of functionality is embodied in a specific web sitecontrolled by an entity such as a business or service provider. Thismodel fits conventional Internet services deployment in whichfunctionality is statically bound to one or more specific network nodes.In one respect, the present invention can be viewed as an augmentationof this conventional model that enables functionality to be distributedfrom its statically assigned location to a variety of dynamicallyassigned nodes that implement the web site's functionality. In a secondaspect, the present invention contemplates that the entity-controlledweb site may exist only virtually (e.g., none of the web sitefunctionality is statically bound to a particular node) and that all ofthe site functionality is embodied in the nodes to which thefunctionality is distributed.

[0023] The present invention is illustrated and described in terms of adistributed computing environment such as an enterprise computing systemusing public communication channels such as the Internet. However, animportant feature of the present invention is that it is readily scaledupwardly and downwardly to meet the needs of a particular application.Accordingly, unless specified to the contrary, the present invention isapplicable to significantly larger, more complex network environments,including wireless network environments, as well as small networkenvironments such as conventional LAN systems.

[0024] The present invention is particularly useful in applicationswhere there is an large amount of data communicated between web serversand web clients (i.e., browser software) or where timeliness (e.g., lowlatency transport) is important. For example, real-time stock quotes,multi-player games, multi-tiered service to ASP (application serviceprovider) software distribution models benefit from the improvementsprovided by the present invention. Although the present invention willbe described in terms of particular applications, these examples areprovided to enhance understanding and are not a limitation of theessential teachings of the present invention.

[0025] The current experience of using an overloaded, topologicallydistant or unavailable web site that is one of frustration and constantand unexplained errors. In terms of conventional phone-order shopping,this is akin to a customer phoning a favorite mail order company only toreceive a constant busy signal or non-stop ringing or to be connected toan operator only to be disconnected prior to the completion of the orderplacement. Under the present invention, web site operators have amechanism to communicate with their customers even if they cannot handletheir web query immediately. One aspect of the present invention is anability to serve alternative content and/or functionality in response toa request for particular content and/or functionality. For example, theinvention contemplates a system that presents the user with apre-defined set of web pages which can apologize for delays, instructthe user on what to do in case of an emergency, advertise additionaloptions or new product offerings, and/or provide other functionalitysuch as call-center type features including queue management.

[0026] The present invention uses a web site delivery system in which aplurality of front-end web servers and back-end web servers cooperate todeliver content and services of the web site. A front-end web server isan application program that is enabled to generate web pages (e.g., HTMLpages) in response to HTTP requests received from a client softwareapplication such as a web browser. A back-end or “originating” webserver is a software application that receives requests from thefront-end web server and is logically close to one or more networkresources (e.g., data storage, database servers, and the like). The term“logically close” as used herein refers to quality of service betweentwo points and may reflect physical proximity, topological proximity orother factors that affect quality of service and speed of servicebetween two points.

[0027] A web site is conventionally implemented by including all thefunctionality implemented by the web site in a web server or web serversthat are logically close to the network resources to be served by thatweb site. In contrast, the present invention implements web sitefunctionality and behavior within one or more front-end web server(s)that communicate over the public network or WAN to obtain the networkresources or possess the network resources locally. Preferably, thefront-end web server includes an enhanced communication channel forcommunicating with the back-end web server. This shift in functionalityfrom the back-end to the front-end provides improved performance in manyapplications. CPU intensive processing can be performed by the front-endserver thereby relieving the back-end web server to handle requests.Also, because multiple front-ends may access the same back-end servers,the CPU intensive functionality is distributed over a larger number ofmachines as needed to provide improved performance and access to alarger number of clients.

[0028] For purposes of this document, a web server is a computer runningserver software coupled to the World Wide Web (i.e., “the web”) thatdelivers or serves web pages. The web server has a unique IP address andaccepts connections in order to service requests by sending backresponses. A web server differs from a proxy server or a gateway serverin that a web server has resident a set of resources (i.e., softwareprograms, data storage capacity, and/or hardware) that enable it toexecute programs to provide an extensible range of functionality such asgenerating web pages, accessing remote network resources, analyzingcontents of packets, reformatting request/response traffic and the likeusing the resident resources. In contrast, a proxy simply forwardsrequest/response traffic on behalf of a client to resources that resideelsewhere, or obtains resources from a local cache if implemented. A webserver in accordance with the present invention may reference externalresources of the same or different type as the services requested by auser, and reformat and augment what is provided by the externalresources in its response to the user. Commercially available web serversoftware includes Microsoft Internet Information Server (IIS), NetscapeNetsite, Apache, among others. Alternatively, a web site may beimplemented with custom or semi-custom software that supports HTTPtraffic.

[0029]FIG. 1 shows an exemplary computing environment 100 in which thepresent invention may be implemented. Environment 100 includes aplurality of local networks such as Ethernet network 102, FDDI network103 and Token ring network 104. Essentially, a number of computingdevices and groups of devices are interconnected through a network 101.For example, local networks 102, 103 and 104 are each coupled to network101 through routers 109. LANs 102, 103 and 104 may be implemented usingany available topology and may implement one or more server technologiesincluding, for example UNIX, Novell, or Windows NT networks, orpeer-to-peer type network. Each network will include distributed storageimplemented in each device and typically includes some mass storagedevice coupled to or managed by a server computer. Network 101comprises, for example, a public network such as the Internet or anothernetwork mechanism such as a fibre channel fabric or conventional WANtechnologies.

[0030] Local networks 102, 103 and 104 include one or more networkappliances 107. One or more network appliances 107 may be configured asan application and/or file server. Each local network 102, 103 and 104may include a number of shared devices (not shown) such as printers,file servers, mass storage and the like. Similarly, devices 111 may beshared through network 101 to provide application and file services,directory services, printing, storage, and the like. Routers 109 providea physical connection between the various devices through network 101.Routers 109 may implement desired access and security protocols tomanage access through network 101. Network appliances 107 may alsocouple to network 101 through public switched telephone network 108using copper or wireless connection technology. In a typicalenvironment, an Internet service provider 106 supports a connection tonetwork 101 as well as PSTN 108 connections to network appliances 107.

[0031] Network appliances 107 may be implemented as any kind of networkappliance having sufficient computational function to execute softwareneeded to establish and use a connection to network 101. Networkappliances 107 may comprise workstation and personal computer hardwareexecuting commercial operating systems such as Unix variants, MicrsosoftWindows, Macintosh OS, and the like. At the same time, some appliances107 comprise portable or handheld devices using wireless connectionsthrough a wireless access provider such as personal digital assistantsand cell phones executing operating system software such as PalmOS,WindowsCE, and the like. Moreover, the present invention is readilyextended to network devices such as office equipment, vehicles, andpersonal communicators that make occasional connection through network101.

[0032] Each of the devices shown in FIG. 1 may include memory, massstorage, and a degree of data processing capability sufficient to managetheir connection to network 101. The computer program devices inaccordance with the present invention are implemented in the memory ofthe various devices shown in FIG. 1 and enabled by the data processingcapability of the devices shown in FIG. 1. In addition to local memoryand storage associated with each device, it is often desirable toprovide one or more locations of shared storage such as disk farm (notshown) that provides mass storage capacity beyond what an individualdevice can efficiently use and manage. Selected components of thepresent invention may be stored in or implemented in shared massstorage.

[0033]FIG. 2a-FIG. 2d illustrate entity relationships involved in aninteraction in which functionality provided by an originating web site210 is provided from a variety of sources including front-ends 201. Asingle client 205 is shown in FIG. 2a-FIG. 2d, however, a number ofclients will be enabled to use the system simultaneously. Each client205 has a network connection that supports a communication channel toone or more originating servers 210 in which a particular web site isimplemented.

[0034] In a typical client-server transaction shown in FIG. 2a, a clientmakes a request for resources and/or functionality implemented onoriginating server 210. In a web-based implementation, this requesttakes the form of an HTTP request datagram specifying a uniform resourcelocator (URL) that identifies originating server 210. As in conventionalnetworks, various routing actions are taken within network 101(described below) to direct the request datagram to its intendeddestination. In a conventional environment, client 205 waits for aresponse to the request datagram.

[0035] Management component 207 shown in FIG. 2c, in practice, embodiesa number of routing and control functions that may be implemented in anumber of servers as opposed to the single entity shown in FIG. 2b-FIG.2c.Mechanisms shown in FIG. 4 are used to redirect client 205 to one ofa plurality of front-end servers 201 shown in FIG. 2c. Another functionof management component 207 is to dynamically maintain and shift contentand functionality between originating server 210 and the variousavailable front-end machines 201. In a particular implementation,management component 207 maintains an outof-band or in-band connection202 with each front-end server 201 and each originating server 210.Connection 202 enables the dynamic shifting of functionality as neededto meet the needs of a particular application.

[0036] Unlike conventional networks, the present invention operates asshown in FIG. 2b to route the request from client 205 to a particularfront-end 201 that is able to respond to the request from client 205 asshown in FIG. 2d. Non-selected front-ends 201, shown in phantom in FIG.2d, are not involved in responding to the request. Preferably, client205 is unaware that content and/or functionality is being provided by anentity other than originating server 210. In fact, it is contemplatedthat originating server 210 may not exist in a physical sense at all. Solong as the desired functionality is provided by the availablefront-ends 201, originating server 210 may become unnecessary as aphysical entity.

[0037] Management component 207 may shift functionality after therequest is received, or proactively before the request is received basedon predictive logic. Front-end servers may cache or locally storecontent and program code that are frequently used to control delays inporting functionality between nodes. It is contemplated that managementcomponent may select originating server 210 itself in some circumstancesto provide content and functionality that is most efficiently deployedat a particular time or in particular circumstances by server 210. Inthis manner, functionality, content, and behavior is dynamically shiftedamongst available resources.

[0038] In a particular example, management component 207 measures andmaintains metrics associated with each front-end server 201 over channel202. These metrics include, for example, processor load, quality ofservice between various points, memory resource load, and othermeasurements that impact the ability of a front-end server toefficiently respond to requests. Management component 207 uses thesemetrics in the selection of a particular front-end 201 to respond to aparticular request. Preferably, management component 207 also maintainsan inventory of the content and functionality available at eachfront-end server 201 so that requests can be directed to a front-endthat is already configured to provide the desired functionality.

[0039] In the preferred web-based implementation, front-end servers 201are implemented by web server software that supports dynamic expansionof functionality. Several commercial off-the-shelf web server packagesoffer such extensible functionality through the use of plug-ins,servelets, agents and other modular program components. In some cases,it is contemplated that special purpose web server software will be usedin front-ends 201 that implement more streamlined and compact softwarethan is possible with off-the-shelf general purpose products. It iscontemplated that any computer upon which front-end 201 executes willsupport multiple instances of front-end 201. In other words, a networknode upon which a front-end 201 resides may actually have multiplefront-ends 201 in existence at any given time. In this specific example,client 205 comprises a network-enabled graphical user interface such asa World Wide Web (web) browser. However, the present invention isreadily extended to client software other than conventional web browsersoftware. Any client application that can access a standard orproprietary user level protocol or language for network access is asuitable equivalent. For convenience, the term “web site” is usedinterchangeably with “web server” in the description herein although itshould be understood that a web site comprises a collection of content,programs and processes implemented on one or more web servers. A website is owned by the content provider such as an e-commerce vendorwhereas a web server refers to set of programs running on one or moremachines coupled to an Internet, intranet, or other network node. Theweb site 210 may be hosted on the site owner's own web server, or hostedon a web server owned by a third party. A web hosting center is anentity that implements one or more web sites on one or more web serversusing shared hardware and software resources across the multiple websites. In a typical web infrastructure, there are many web browsers,each of which has a TCP connection to the web server in which aparticular web site is implemented. The present invention adds twocomponents to the infrastructure: a front-end 201 and back-end 203.Front-end 201 and back-end 203 are coupled by a managed datacommunication link 202 that forms, in essence, a private network.

[0040]FIG. 3 shows a particular implementation of the functionalityshifting system of FIG. 2a-FIG. 2d. that uses not only front-end servers201, but also one or more back-end servers 203 to further improvefunctionality shifting performance. In the particular implementationshown in FIG. 3, functionality can be served from originating server210, back-end server 203 and/or front-end servers 201 as needed to meetthe needs of a particular application.

[0041] In FIG. 3, a private network 200 implemented within the Internetinfrastructure. Private network 200 expedites and prioritizescommunications between a client 205 and a web site 210. In the specificexamples herein client 205 comprises a network-enabled graphical userinterface such as a web browser. However, the present invention isreadily extended to client software other than conventional web browsersoftware. Any client application that can access a standard orproprietary user level protocol for network access is a suitableequivalent. Examples include client applications for file transferprotocol (FTP) services, voice over Internet protocol (VOIP) services,network news protocol (NNTP) services, multi-purpose Internet mailextensions (MIME) services, post office protocol (POP) services, simplemail transfer protocol (SMTP) services, as well as Telnet services. Inaddition to network protocols, the client application may access anetwork application such as a database management system (DBMS) in whichcase the client application generates query language (e.g., structuredquery language or “SQL”) messages. In wireless appliances, a clientapplication may communicate via a wireless application protocol (WAP) orthe like.

[0042] Front-end mechanism 201 serves as an access point for client-sidecommunications. Front-end 201 implements a gateway that, from theperspective of client 205, appears to be the web site 210. Front-end 201comprises, for example, a computer that sits “close” to clients 205. By“close”, it is meant that the average latency associated with aconnection between a client 205 and a front-end 201 is less than theaverage latency associated with a connection between a client 205 and aweb site 210. Desirably, the connection between front-end computers andclients 205 have low latency and high bandwidth. For example, thefastest available connection may be implemented in point of presence(POP) of an Internet service provider (ISP) 106 used by a particularclient 205. However, the placement of the front-ends 201 can limit thenumber of browsers that can use them. Because of this, in someapplications, it may be more practical to place one front-end computerin such a way that several POPs can connect to it. Greater distancebetween frontend 201 and clients 205 may be desirable in someapplications as this distance will allow for selection amongst a greaternumber front-ends 201 and thereby provide significantly different routesto a particular back-end 203. This may offer benefits when particularroutes and/or front-ends become congested or otherwise unavailable.

[0043] Enhanced communication channel 212 is implemented by cooperativeactions of the front-end 201 and back-end 203. Back-end 203 processesand directs data communication to and from originating server 210. In aparticular example, transport mechanism 212 communicates data packetsusing a proprietary protocol over the Internet. Hence, the presentinvention does not require heavy infrastructure investments andautomatically benefits from improvements implemented in thegeneral-purpose network 101. Unlike the general purpose Internet,front-end 201 and back-end 203 may be assigned to serve accesses to oneor more particular originating servers 210 at any given time.

[0044] It is contemplated that any number of front-end and back-endmechanisms may be implemented cooperatively to support the desired levelof service required by the web site owner. The present inventionimplements a many-to many mapping of front-ends to back-ends. Becausethe front-end to back-end mappings can by dynamically changed, a fixedhardware infrastructure can be logically reconfigured to map more orfewer front-ends to more or fewer back-ends and web sites or servers asneeded.

[0045] Front-end 201 together with back-end 203 function to reducetraffic across the transport morphing protocol TMPTM link 212 and toimprove response time for selected browsers. Traffic across the TMP link212 is reduced by compressing data and serving browser requests fromcache for fast retrieval. Also, the blending of request datagramsresults in significantly fewer request:acknowledge pairs across the TMPlink 212 as compared to the number required to reliably send the packetsindividually between front-end 201 and back-end 203. This action reducesthe overhead associated with transporting a given amount of data,although conventional request:acknowledge traffic is still performed onthe links coupling the front-end 201 to client 205 and back is end 203to a web server. Moreover, resend traffic is significantly reducedfurther reducing the traffic. Response time is further improved forselect privileged users and for specially marked resources bydetermining the priority for each HTTP transmission.

[0046] In one embodiment, front-end 201 and back-end 203 are closelycoupled to the Internet backbone. This means they have high bandwidthconnections, can expect fewer hops, and have more predictable packettransit time than could be expected from a general-purpose connection.Although it is preferable to have low latency connections betweenfront-ends 201 and back-ends 203, a particular strength of the presentinvention is its ability to deal with latency by enabling efficienttransport and traffic prioritization. Hence, in other embodimentsfront-end 201 and/or back-end 203 may be located farther from theInternet backbone and closer to clients 205 and/or web servers 210. Suchan implementation reduces the number of hops required to reach afront-end 201 while increasing the number of hops within the TMP link212 thereby yielding control over more of the transport path to themanagement mechanisms of the present invention.

[0047] Clients 205 no longer conduct all data transactions directly withthe web server 210. Instead, clients 205 conduct some and preferably amajority of transactions with front-ends 201, which simulate thefunctions of web server 210. Client data is then sent, using TMP link212, to the back-end 203 and then to the web server 210. Runningmultiple clients 205 over one large connection provides severaladvantages:

[0048] Since all client data is mixed, each client can be assigned apriority. Higher priority clients, or clients requesting higher prioritydata, can be given preferential access to network resources so theyreceive access to the channel sooner while ensuring low-priority clientsreceive sufficient service to meet their needs.

[0049] The large connection between a front-end 201 and back-end 203 canbe permanently maintained, shortening the many TCP/IP connectionsequences normally required for many clients connecting anddisconnecting.

[0050] Using a proprietary protocol allows the use of more effectivetechniques to improve data throughput and permits better use of existingbandwidth during periods when the network is congested.

[0051] A particular advantage of the architectures shown in FIG. 2a-FIG.2d and FIG. 3 is that it is readily scaled. Any number of clientmachines 205 may be supported. In a similar manner, a web site owner maychoose to implement a site using multiple web servers 210 that areco-located or distributed throughout network 101. To avoid congestion,additional front-ends 201 may be implemented or assigned to particularweb sites. Each front-end 201 is dynamically re-configurable by updatingaddress parameters to serve particular web sites. Client traffic isdynamically directed to available front-ends 201 to provide loadbalancing. Hence, when quality of service drops because of a largenumber of client accesses, an additional front-end 201 can be assignedto the web site and subsequent client requests directed to the newlyassigned front-end 201 to distribute traffic across a broader base.

[0052] In the particular examples, this is implemented by a front-endmanager component 217 that communicates with multiple front-ends 201 toprovide administrative and configuration information to front-ends 201.Each frontend 201 includes data structures for storing the configurationinformation, including information identifying the back-ends 203 of webservers 210 to which they are currently assigned. Other administrativeand configuration information stored in front-end 201 may includeinformation for prioritizing specific data from and to particularclients, quality of service information, and the like.

[0053] Similarly, additional back-ends 203 can be assigned to a web siteto handle increased traffic. Back-end manager component 219 couples toone or more back-ends 203 to provide centralized administration andconfiguration service. Back-ends 203 include data structures to holdcurrent configuration state, quality of service information and thelike. In the particular examples, front-end manager 217 and back-endmanager 219 serve multiple web sites 210 and so are able to manipulatethe number of front-ends and back-ends assigned to each web site 210 byupdating this configuration information. When the congestion for thesite subsides, the front-ends 201 and back-ends 203 can be reassigned toother, busier web sites. These and similar modifications are equivalentto the specific examples illustrated herein.

[0054] In the case of web-based environments, front-end 201 isimplemented using custom or off-the-shelf web server software. Front-end201 is readily extended to support other, non-web-based protocols,however, and may support multiple protocols for varieties of clienttraffic. Front-end 201 processes the data traffic it receives,regardless of the protocol of that traffic, to a form suitable fortransport by TMP 212 to a back-end 203. Hence, most of the functionalityimplemented by front-end 201 is independent of the protocol or format ofthe data received from a client 205. Hence, although the discussion ofthe exemplary embodiments herein relates primarily to front-end 201implemented as a web server, it should be noted that, unless specifiedto the contrary, web-based traffic management and protocols are merelyexamples and not a limitation of the present invention.

[0055] As shown in FIG. 2, in accordance with the present invention aweb site is implemented using an originating web server 210 operatingcooperatively with the web server of front-end 201. More generally, anynetwork service (e.g., FTP, VoIP, NNTP, MIME, SMTP, Telnet, DBMS) can beimplemented using a combination of an originating server workingcooperatively with a front-end 201 configured to provide a suitableinterface (e.g., FTP , VOIP, NNTP, MIME, SMTP, Telnet, DBMS, WAP) forthe desired service. In contrast to a simple front-end cache or proxysoftware, implementing a server in front-end 201 enables portions of theweb site (or other network service) to actually be implemented in andserved from both locations. The actual web pages or service beingdelivered comprises a composite of the portions generated at eachserver. Significantly, however, the web server in front-end 201 is closeto the browser in a client 205 whereas the originating web server isclose to all resources available at the web hosting center at which website 210 is implemented. In essence the web site 210 is implemented by atiered set of web servers comprising a front-end server 201 standing infront of an originating web server.

[0056] This difference enables the web site functionality to beimplemented and distributed so as to take advantage of the uniqueposition each web server has with respect to the client 205. By way of aparticular example, assume an environment in which the front-end webserver 201 is located in the ISP's location for a particular set ofclients 205. In such an environment, clients 205 can access thefront-end web server 205 without actually traversing the network 101.Hence, network delays and variability are substantially eliminated.

[0057] In order for a client 205 to obtain service from a front-end 201,it must first be directed to a front-end 201 that can provide thedesired service. FIG. 4 illustrates a domain name server (DNS)redirection mechanism that illustrates an example of how a client 205 isconnected to a particular front-end 201. Preferably, client 205 does notneed to be aware of the location of front-end 201, and initiates alltransactions as if it were contacting the originating server 210. Thepublic DNS system is defined in a variety of Internet Engineering TaskForce (IETF) documents such as RFC0883, RFC 1034 and RFC 1035 which areincorporated by reference herein. In a typical environment, a client 205executes a browser 301, TCP/IP stack 303, and a resolver 305. Forreasons of performance and packaging, browser 301, TCP/IP stack 303 andresolver 305 are often grouped together as routines within a singlesoftware product.

[0058] Browser 301 functions as a graphical user interface to implementuser input/output (I/O) through monitor 311 and associated keyboard,mouse, or other user input device (not shown). Browser 301 is usuallyused as an interface for web-based applications, but may also be used asan interface for other applications such as email and network news, aswell as special-purpose applications such as database access, telephony,and the like. Alternatively, a special-purpose user interface may besubstituted for the more general-purpose browser 301 to handle aparticular application.

[0059] TCP/IP stack 303 communicates with browser 301 to convert databetween formats suitable for browser 301 and IP format suitable forInternet traffic. TCP/IP stack also implements a TCP protocol thatmanages transmission of packets between client 205 and an Internetservice provider (ISP) or equivalent access point. IP protocol requiresthat each data packet include, among other things, an IP addressidentifying a destination node. In current implementations the IPaddress comprises a 32-bit value that identifies a particular Internetnode. Non-IP networks have similar node addressing mechanisms. Toprovide a more user-friendly addressing system, the Internet implementsa system of domain name servers that map alpha-numeric domain names tospecific IP addresses. This system enables a name space that is moreconsistent reference between nodes on the Internet and avoids the needfor users to know network identifiers, addresses, routes and similarinformation in order to make a connection.

[0060] The domain name service is implemented as a distributed databasemanaged by domain name servers (DNSs) 307 such as DNS_A, DNS_B and DNS_Cshown in FIG. 3. Each DNS relies on <domain name:IP> address mappingdata stored in master files scattered through the hosts that use thedomain system. These master files are updated by local systemadministrators. Master files typically comprise text files that are readby a local name server, and hence become available through the nameservers 307 to users of the domain system.

[0061] The user programs (e.g., clients 205) access name servers throughstandard programs such as resolver 305. Resolver 305 includes an addressof a DNS 307 that serves as a primary name server. When presented with areference to a domain name (e.g., http://www.circadence.com), resolver305 sends a request to the primary DNS (e.g., DNS_A in FIG. 3). Theprimary DNS 307 returns either the IP address mapped to that domainname, a reference to another DNS 307 which has the mapping information(e.g., DNS_B in FIG. 3), or a partial IP address together with areference to another DNS that has more IP address information. Anynumber of DNS-to-DNS references may be required to completely determinethe IP address mapping.

[0062] In this manner, the resolver 305 becomes aware of the IP addressmapping which is supplied to TCP/IP component 303. Client 205 may cachethe IP address mapping for future use. TCP/IP component 303 uses themapping to supply the correct IP address in packets directed to aparticular domain name so that reference to the DNS system need onlyoccur once.

[0063] In accordance with the present invention, at least one DNS server307 is owned and controlled by system components of the presentinvention. When a user accesses a network resource (e.g., a web site),browser 301 contacts the public DNS system to resolve the requesteddomain name into its related IP address in a conventional manner. In afirst embodiment, the public DNS performs a conventional DNS resolutiondirecting the browser to an originating server 210 and server 210performs a redirection of the browser to the system owned DNS server(i.e., DNC_C in FIG. 3). In a second embodiment, domain:address mappingswithin the DNS system are modified such that resolution of the of theoriginating server's domain automatically return the address of thesystemowned DNS server (DNS_C). Once a browser is redirected to thesystem-owned DNS server, it begins a process of further redirecting thebrowser 301 to the best available front-end 201.

[0064] Unlike a conventional DNS server, however, the system-owned DNS_Cin FIG. 3 receives domain:address mapping information from a redirectorcomponent 309. Redirector 309 is in communication with front-end manager217 and back-end manager 219 to obtain information on current front-endand back-end assignments to a particular server 210. A conventional DNSis intended to be updated infrequently by reference to its associatedmaster file. In contrast, the master file associated with DNS_(C) isdynamically updated by redirector 309 to reflect current assignment offront-end 201 and back-end 203. In operation, a reference to web server210 (e.g., http://www.circadence.com) may result in an IP addressreturned from DNS_C that points to any selected front-end 201 that iscurrently assigned to web site 210. Likewise, web site 210 may identifya currently assigned back-end 203 by direct or indirect reference toDNS_C.

[0065] Front-end 201 typically receives information directly fromfront-end manager 217 about the address of currently assigned back-ends203. Similarly, back-end 203 is aware of the address of a front-end 201associated with each data packet. Hence, reference to the domain systemis not required to map a front-end 201 to its appropriate backend 203.

[0066]FIG. 5 illustrates principle functional components of an exemplaryfront-end 201 in greater detail. Primary functions of the front-end 201include translating transport control protocol (TCP) packets from client205 into TMP packets used in the system in accordance with the presentinvention. Transport morphing protocol™ and TMP™are trademarks orregistered trademarks of Circadence Corporation in the United States andother countries. It is contemplated that the various functions describedin reference to the specific examples may be implemented using a varietyof data structures and programs operating at any location in adistributed network. For example, a front-end 201 may be operated on anetwork appliance 107 or server within a particular network 102, 103, or104 shown in FIG. 1. The present invention is readily adapted to anyapplication where multiple clients are coupling to a centralizedresource. Moreover, other transport protocols may be used, includingpublic and proprietary transport protocols.

[0067] TCP component 401 includes devices for implementing physicalconnection layer and Internet protocol (IP) layer functionality. CurrentIP standards are described in IETF documents RFC0791, RFC0950, RFC0919,RFC0922, RFC792, RFC1112 that are incorporated by reference herein. Forease of description and understanding, these mechanisms are notdescribed in great detail herein. Where protocols other than TCP/IP areused to couple to a client 205, TCP component 401 is replaced oraugmented with an appropriate network protocol process.

[0068] TCP component 401 communicates TCP packets with one or moreclients 205. Received packets are coupled to parser 402 where theInternet protocol (or equivalent) information is extracted. TCP isdescribed in IETF RFC0793 which is incorporated herein by reference.Each TCP packet includes header information that indicates addressingand control variables, and a payload portion that holds the user-leveldata being transported by the TCP packet. The user-level data in thepayload portion typically comprises a user-level network protocoldatagram.

[0069] Parser 402 analyzes the payload portion of the TCP packet. In theexamples herein, HTTP is employed as the user-level protocol because ofits widespread use and the advantage that currently available browsersoftware is able to readily use the HTTP protocol. In this case, parser402 comprises an HTTP parser. More generally, parser 402 can beimplemented as any parser-type logic implemented in hardware or softwarefor interpreting the contents of the payload portion. Parser 402 mayimplement file transfer protocol (FTP), mail protocols such as simplemail transport protocol (SMTP), structured query language (SQL) and thelike. Any user-level protocol, including proprietary protocols, may beimplemented within the present invention using appropriate modificationof parser 402.

[0070] To improve performance, front-end 201 optionally includes acaching mechanism 403. Cache 403 may be implemented as a passive cachethat stores frequently and/or recently accessed web pages or as anactive cache that stores network resources that are anticipated to beaccessed. In non-web applications, cache 403 may be used to store anyform of data representing database contents, files, program code, andother information. Upon receipt of a TCP packet, HTTP parser 402determines if the packet is making a request for data within cache 403.If the request can be satisfied from cache 403, the data is supplieddirectly without reference to web server 210 (i.e., a cache hit). Cache403 implements any of a range of management functions for maintainingfresh content. For example, cache 403 may invalidate portions of thecached content after an expiration period specified with the cached dataor by web sever 210. Also, cache 403 may proactively update the cachecontents even before a request is received for particularly important orfrequently used data from web server 210. Cache 403 evicts informationusing any desired algorithm such as least recently used, leastfrequently used, first in/first out, or random eviction. When therequested data is not within cache 403, a request is processed to webserver 210, and the returned data may be stored in cache 403.

[0071] Several types of packets will cause parser 402 to forward arequest towards web server 210. For example, a request for data that isnot within cache 403 (or if optional cache 403 is not implemented) mayrequire a reference to web server 210. Some packets will comprise datathat need be supplied to web server 210 (e.g., customer creditinformation, form data and the like) . In these instances, HTTP parser402 couples to data blender 404.

[0072] Optionally, front-end 201 implements security processes,compression processes, encryption processes and the like to conditionthe received data for improved transport performance and/or provideadditional functionality. These processes may be implemented within anyof the functional components (e.g., data blender 404) or implemented asseparate functional components within front-end 201. Also, parser 402may implement a prioritization program to identify packets that shouldbe given higher priority service. A prioritization program requires onlythat parser 402 include a data structure associating particular clients205 or particular TCP packet types or contents with a prioritizationvalue. Based on the prioritization value, parser 402 may selectivelyimplement such features as caching, encryption, security, compressionand the like to improve performance and/or additional functionality. Theprioritization value is provided by the owners of web site 210, forexample, and may be dynamically altered, statically set, or updated fromtime to time to meet the needs of a particular application.

[0073] Blender 404 slices and/or coalesces the data portions of thereceived packets into a more desirable “TMP units” that are sized fortransport through the TMP mechanism 212. The data portion of TCP packetsmay range in size depending on client 205 and any intervening linkscoupling client 205 to TCP component 401. Moreover, where compression isapplied, the compressed data will vary in size depending on thecompressibility of the data. Data blender 404 receives information fromfront-end manager 217 that enables selection of a preferable TMP packetsize. Alternatively, a fixed TMP packet size can be set that yieldsdesirable performance across TMP mechanism 212. Data blender 404 alsomarks the TMP units so that they can be re-assembled at the receivingend.

[0074] Data blender 404 may also serve as a buffer for storing packetsfrom all appliances 177 that are associated with front-end 201. Inaccordance with the present invention, data blender 404 may associate aprioritization value with each packet.

[0075] In an exemplary implementation, a “TMP connection” comprises aplurality of “TCP connection buffers”, logically arranged in multiple“rings”. Each TCP socket maintained between the front-end 201 and aclient 205 corresponds to a TCP connection buffer. When a TCP connectionbuffer is created, it is assigned a priority. For purposes of thepresent invention, any algorithm or criteria may be used to assign apriority. Each priority ring is associated with a number of TCPconnection buffers sockets having similar priority. In a specificexample, five priority levels are defined corresponding to five priorityrings. Each priority ring is characterized by the number of connectionbuffers it holds (nsockets), the number of connection buffers it holdsthat have data waiting to be sent (nReady) and the total number of bytesof data in all the connection buffers that it holds (nBytes).

[0076] When composing TMP data packets, the blender goes into a loopcomprising the steps:

[0077] 1) Determine the number of bytes available to be sent from eachring (nBytes), and the number of TCP connections that are ready to send(nready)

[0078] 2) Determine how many bytes should be sent from each ring(nSend). This is based on a weight parameter for each priority. Theweight can be thought of as the number of bytes that should be sent ateach priority this time through the loop.

[0079] 3) The nSend value computed in the previous step reflects theweighted proportion that each ring will have in a blended TMP packet,but the values of nSend do not reflect how many bytes need to beselected to actually empty most or all of the data waiting to be sent asingle round. To do this, the nSend value is normalized to the ringhaving the most connections waiting. This involves a calculation of afactor: S=nBytes/(Weight*nReady) for the ring with the greatest nReady.Then, for each ring, calculate nSend×S to get the normalized value(nSendNorm) for each priority ring.

[0080] 4) Send sub-packets from the different rings. This is done bytaking a sub-packet from the highest priority ring and adding it to aTMP packet, then adding a sub-packet from each of the top two queues,then the top three, and so on.

[0081] 5) Within each ring, sub-packets are selected round robin. When asub-packet is selected from a TCP connection buffer the ring is rotatedso the next subpacket the ring adds will come from a different TCPconnection buffer. Each sub-packet can be up to 512 bytes in aparticular example. If the connection buffer has less than 512 byteswaiting, the data available is added to the TMP packet.

[0082] 6) When a full TMP packet (roughly 1.5 kB in a particularexample)is built, it is sent. This will usually have three or moresub-packets, depending on their size. The TMP packet will also be sentwhen there is no more data ready.

[0083] TMP mechanism 405 implements the TMP protocol in accordance withthe present invention. TMP is a TCP-like protocol adapted to improveperformance for multiple channels operating over a single connection.Front-end TMP mechanism 405 and a corresponding back-end TMP mechanism505 shown in FIG. 6 are computer processes that implement the end pointsof TMP link 212. The TMP mechanism in accordance with the presentinvention creates and maintains a stable connection between twoprocesses for high-speed, reliable, adaptable communication.

[0084] TMP is not merely a substitute for the standard TCP environment.TMP is designed to perform particularly well in heterogeneous networkenvironments such as the Internet. TMP connections are made less oftenthan TCP connections. Once a TMP connection is made, it remains upunless there is some kind of direct intervention by an administrator orthere is some form of connection breaking network error. This reducesoverhead associated with setting up, maintaining and tearing downconnections normally associated with TCP.

[0085] Another feature of TMP is its ability to channel numerous TCPconnections through a single TMP pipe 212. The environment in which TMPresides allows multiple TCP connections to occur at one end of thesystem. These TCP connections are then mapped into a single TMPconnection. The TMP connection is then broken down at the other end ofthe TMP pipe 212 in order to traffic the TCP connections to theirappropriate destinations. TMP includes mechanisms to ensure that eachTMP connection gets enough of the available bandwidth to accommodate themultiple TCP connections that it is carrying.

[0086] Another advantage of TMP as compared to traditional protocols isthe amount of information about the quality of the connection that a TMPconnection conveys from one end to the other of a TMP pipe 212. As oftenhappens in a network environment, each end has a great deal ofinformation about the characteristics of the connection in onedirection, but not the other. By knowing about the connection as awhole, TMP can better take advantage of the available bandwidth.

[0087] In contrast with conventional TCP mechanisms, the behaviorimplemented by TMP mechanism 405 is constantly changing. Because TMPobtains bandwidth to host a variable number of TCP connections andbecause TMP is responsive information about the variable status of thenetwork, the behavior of TMP is preferably continuously variable. One ofthe primary functions of TMP is being able to act as a conduit formultiple TCP connections. As such, a single TMP connection cannot behavein the same manner as a single TCP connection. For example, imagine thata TMP connection is carrying 100 TCP connections. At this time, it losesone packet (from any one of the TCP connections) and quickly cuts itswindow size in half (as specified for TCP) . This is a performancereduction on 100 connections instead of just on the one that lost thepacket.

[0088] Each TCP connection that is passed through the TMP connectionmust get a fair share of the bandwidth, and should not be easilysqueezed out. To allow this to happen, every TMP becomes more aggressivein claiming bandwidth as it accelerates. Like TCP, the bandwidthavailable to a particular TMP connection is measured by its window size(i.e., the number of outstanding TCP packets that have not yet beenacknowledged). Bandwidth is increased by increasing the window size, andrelinquished by reducing the window size. Up to protocol specifiedlimits, each time a packet is successfully delivered and acknowledged,the window size is increased until the window size reaches a protocolspecified maximum. When a packet is dropped (e.g., no acknowledgereceived or a resend packet response is received), the bandwidth isdecreased by backing off the window size. TMP also ensures that itbecomes more and more resistant to backing off (as compared to TCP) witheach new TCP connection that it hosts. A TMP should not go down to awindow size of less than the number of TCP connections that it ishosting.

[0089] In a particular implementation, every time a TCP connection isadded to (or removed from) what is being passed through the TMPconnection, the TMP connection behavior is altered. It is thisadaptation that ensures successful connections using TMP. Through theuse of the adaptive algorithms discussed above, TMP is able to adapt theamount of bandwidth that it uses. When a new TCP connection is added tothe TMP connection, the TMP connection becomes more aggressive. When aTCP connection is removed from the TMP connection, the TMP connectionbecomes less aggressive.

[0090] TMP pipe 212 provides improved performance in its environment ascompared to conventional TCP channels, but it is recognized that TMPpipe 212 resides on the open, shared Internet in the preferredimplementations. Hence, TMP must live together with many protocols andshare the pipe efficiently in order to allow the other transportmechanisms fair access to the shared communication bandwidth. Since TMPtakes only the amount of bandwidth that is appropriate for the number ofTCP connections that it is hosting (and since it monitors the connectionand controls the number of packets that it puts on the line), TMP willexist cooperatively with TCP traffic. Furthermore, since TMP does abetter job at connection monitoring than TCP and TMP is better suited tothroughput and bandwidth management than TCP.

[0091] Also shown in FIG. 5 are data filter component 406 and HTTPreassemble component 407 that process incoming (with respect to client205) data. TMP mechanism 405 receives TMP packets from TMP pipe 212 andextracts the TMP data units. Using the appended sequencing information,the extracted data units are reassembled into HTTP data packetinformation by HTTP reassembler 407. Data filter component 406 may alsoimplement data decompression where appropriate, decryption, and handlecaching when the returning data is of a cacheable type.

[0092]FIG. 6 illustrates principle functional components of an exemplaryback-end 203 in greater detail. Primary functions of the back-end 203include translating transmission control protocol (TCP) packets from webserver 210 into TMP packets as well as translating TMP packets receivedfrom a front-end 201 into the one or more corresponding TCP packets tobe send to server 210. Further, back-end 203 is able to implementsimilar or complementary functionality to that of front-end 203. In thismanner, back-end 203 can operate as a web server to retrieve content andgenerate web pages, analyze and reformat web pages and components withinweb pages, and similar server functionality that would conventionally beimplemented in a server 210. In general, any functionality and behaviordescribed herein that can be implemented on server 210 and/or front-endserver 201 can also be implemented on back-end server 203.

[0093] TMP unit 505 receives TMP packets from TMP pipe 212 and passesthem to HTTP reassemble unit 507 where they are reassembled into thecorresponding TCP packets. Data filter 506 may implement otherfunctionality such as decompression, decryption, and the like to meetthe needs of a particular application. The reassembled data is forwardedto TCP component 501 for communication with web server 210.

[0094] TCP data generated by the web server process are transmitted toTCP component 501 and forwarded to HTTP parse mechanism 502. Parser 502operates in a manner analogous to parser 402 shown in FIG. 5 to extractthe data portion from the received TCP packets, perform optionalcompression, encryption and the like, and forward those packets to datablender 504. Data blender 504 operates in a manner akin to data blender404 shown in FIG. 5 to buffer and prioritize packets in a manner that isefficient for TMP transfer. Priority information is received by, forexample, back-end manager 219 based upon criteria established by the website owner. TMP data is streamed into TMP unit 505 for communication onTMP pipe 212.

[0095]FIG. 7 illustrates a conceptual block diagram of an exemplaryimplementation of the system shown in FIG. 2 in an alternative context.In the example of FIG. 6, frontend 201 is implemented as a front-end webserver 601 operating at an ISP 602. ISP 602 supports modem, digitalsubscriber line (DSL), ISDN, leased line, or other communication portsfor communicating with one or more clients 605. ISP 602 serves as abridge to couple client connections to IP connections with network 101.ISP 602 may be considered to be outside of network 101 in that qualityof service between client 605 and ISP 602 is not dependent on congestionor equipment failure or other factors affecting quality of servicewithin network 101.

[0096] In operation, client 605 generates an HTTP request specifying website 610 in the URL. In the manner described hereinbefore, the clientrequest is redirected to front-end 601. Once the redirection iscompleted, front-end 601 serves web pages embedded in HTTP responsepackets using both content and functionality obtained from web site 610as well as content and functionality present on front-end 601 orobtained from database 603. In this manner, front-end web server 601 candynamically controls the source of the delivered content. The webpage(s) served to client 605 comprise a composite of multiple sourcesfrom multiple independent web servers.

[0097] Significantly, the content served from content database 603 maydiffer from the content and functionality that would have otherwise beenserved by web site 610. For example, if web site 610 returns an HTTP 404“page not found” error page, front-end web site 601 may supply a moreinformative or instructive web page derived from content database 603.Alternatively, front-end web site 601 may detect periods of low qualityof service or slow response and provide substitute content from contentdatabase 603 or elsewhere. In a particular example, web site 610publishes a load index that can be read by frontend 601 and used togenerate a wait page intended to occupy a user of client 605 untilcontent can be obtained directly from web site 610.

[0098] In another embodiment, the desired format of content is specifiedby client 605, information maintained about the desired or requiredformat for client 605 by the system and/or the system can determine therequired format for client 605 and its connection to front-end 601indirectly. In response, front-end web server 601 formats and convertscontent and data to be provided to client 605 based on custom requestsforwarded to web server 610 and/or on a common data set provided bywebsite 610 for purposes of responding to one or more clients 605.

[0099] In a particular example, the owner of web site 610 establishesrules for how front-end web server 601 handles various conditions. Theserules are stored in front-end web server 601. Hence, the owner of website 610 is not losing control over how web site 610 is presented, butinstead is gaining control over how presentation occurs during periodswhere network 101 is unavailable or provides unacceptable quality ofservice. By placing a web server in front of the origin web server 610,overall user experience as well as efficacy of the web site 610 for thesite owner are improved.

[0100] It should be understood that the essence of systems in accordancewith the present invention, i.e., dynamically shifting functionalityamongst a network of servers can be expressed in a variety ofimplementations. For example, a network-connected server may obtainprogram code, data, and other resources to provide a desired set offunctionality either in response to a client request, or independentlyof the client request in a manner that proactively or anticipatorily.Proactive operation allows a network-connected server to maintain a setof functionality such that services can be provided without reference toa central authority when a client request is actually received. In suchcases, processes within the front-end 201, for example, will makerequests to another network-connected server (e.g., another front-end201) or to an originating server 210 to obtain the program code, data,and resources, and then independently respond to client requests usingthe obtained program code, data and resources. The connections betweenfront-ends 201 and origin servers 210 can benefit from features of theenhanced channel 202.

[0101] Any number of front-ends 201 may be involved in providing aparticular service or set of functionality. It is contemplated that aclient 205 may connect to a particular front-end 201 and that particularfront-end 201 may establish connections with one or more other frontends 201 to access functionality, data and resources available in thoseother front-ends.

[0102] Although the invention has been described and illustrated with acertain degree of particularity, it is understood that the presentdisclosure has been made only by way of example, and that numerouschanges in the combination and arrangement of parts can be resorted toby those skilled in the art without departing from the spirit and scopeof the invention, as hereinafter claimed. For example, while devicessupporting HTTP data traffic are used in the examples, the HTTP devicesmay be replaced or augmented to support other public and proprietaryprotocols and languages including FTP, NNTP, SMTP, SQL and the like. Insuch implementations the front-end 201 and/or back end 203 are modifiedto implement the desired protocol. Moreover, front-end 201 and back-end203 may support different protocols and languages such that thefront-end 201 supports, for example, HTTP traffic with a client and theback-end supports a DBMS protocol such as SQL. Such implementations notonly provide the advantages of the present invention, but also enable aclient to access a rich set of network resources with minimal clientsoftware.

We claim:
 1. A system for providing functionality over a networkcomprising: a plurality of network-connected servers, each providingaccess to a set of functions implemented by program components withinthe server; at least one network-connected client computer; a managementcomponent coupled to each of the network-connected servers; a shiftingcomponent within the management component operable to shift data andprogram components between the network-connected servers so as toconfigure a selected server to implement a specified set of functions;and a redirection component responsive to a client request for thespecified set of functions to redirect the requesting client to theselected server.
 2. The system of claim 1 wherein the selected networkserver further comprises: a data storage mechanism; processes responsiveto client requests to accesses data in the data storage mechanism; andprocesses operable to generate a response to the client requests usingthe accessed data.
 3. The system of claim 2 further comprising:processes operating independently of client requests to update datacontained within the data storage mechanism.
 4. The system of claim 2wherein the data storage mechanism comprises a cache.
 5. The system ofclaim 1 wherein the program components implement a database managementsystem interface.
 6. The system of claim 1 wherein at least one of thenetwork-connected servers is designated as a central authority for aparticular set of functions and the program components implementprocesses for communicating with the central authority.
 7. A system forproviding functionality over a network comprising: a plurality ofnetwork-connected servers, each providing access to a set of functionsimplemented by program components within the server; at least onenetwork-connected client computer; and a redirection componentresponsive to a client request for selecting a particular one of thenetwork-connected servers that implements a set of functions suitablefor responding to the client request and redirecting the requestingclient to the selected server.
 8. The system of claim 7 wherein theplurality of network-connected servers comprise: a firstnetwork-connected server in communication with the client; a secondnetwork-connected server in communication with the firstnetwork-connected server, wherein the redirection component operateswithin the first network-connected server to identify and communicatewith the second network-connected server to enable the firstnetwork-connected server to respond to the client request.
 9. The systemof claim 8 wherein the first and second network-connected serverscommunicate with each other over an enhanced communication channel. 10.A system for implementing a web site comprising: a first web serverconfigured to provide a preselected set of content and serviceapplications in response to client requests; a second web serverconfigured to provide a preselected set of content and serviceapplications in response to requests from the first web server; acommunication channel established between the first and second webservers, wherein the web site is implemented by delivering web pagesfrom at least one of the first and second web servers by distributed andcooperative interaction using services and content provided by bothfirst and second web servers.
 11. The system of claim 10 wherein the website includes functionality that is implemented by service applicationsrunning on both the first and second web servers.
 12. The system ofclaim 10 wherein the web site content is provided by the first webserver and the web site functionality is provided by serviceapplications running on the second web server.
 13. The system of claim10 wherein the web site content is provided by the second web server andthe web site functionality is provided by service applications runningon the first web server.
 14. A system for rendering graphicalinformation in a network environment comprising: a network; providing afirst network service for accessing raw data from a data store;providing a second network service configured to obtain the raw datafrom the first network service over the network; application software inthe second network service for rendering a graphic display of the rawdata; and a client interface in the second network service forcommunicating the rendered graphic display from the second networkservice to a client application.
 15. A method for delivering customizedcontent from one or more network services to a client computercomprising the acts of: providing a plurality of network servers eachproviding access to a set of raw data; requesting the content from thenetwork servers; causing the network server to incorporate the raw datainto a “usuable format”; and delivering the “usuable format”from thenetwork server to a client computer.
 16. A system for supplying renderedinformation in a network environment comprising: providing a firstserver for accessing raw data from a data store; providing a secondserver configured to obtain the raw data from the first networkresource; application software in the second server for transforming theraw data into a rendered format; and a client interface in the secondserver for communicating the rendered format from the second server to aclient application.
 17. A system for delivering functionality from anetwork resource comprising: a client machine coupled to a network, theclient machine having a user interface and a preferred format forpresenting data using the user interface; a gateway machine coupled tothe network and having a client interface for receiving requests fromthe client and supplying responses to the client, the gateway machinehaving knowledge of the preferred format; and formatting mechanismswithin the gateway machine for receiving content in a first format fromthe network resource and reformatting the received content to a secondformat for communication to the client machine.